[Bug 639940] Re: sendsigs can kill upstart scripts' child processes prematurely on system shutdown

[Łukasz Zemczak]

** Changed in: sysvinit (Ubuntu)
       Status: Triaged => Won't Fix

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to sysvinit in Ubuntu.
https://bugs.launchpad.net/bugs/639940

Title:
  sendsigs can kill upstart scripts' child processes prematurely on
  system shutdown

Status in sysvinit package in Ubuntu:
  Won't Fix

Bug description:
  Binary package hint: sysvinit

  sendsigs can kill child processes executed as part of upstart
  pre/post-stop scripts. It successfully omits upstart processes
  (daemons and the script processes themselves), but if you use anything
  other than shell builtins in an upstart job script, those shell-
  spawned processes don't wind up in OMITPIDS and killall5 kills them.

  For example, 143 (15/SIGTERM) ends up in /tmp/foo with a script like
  this.

    pre-stop script
      sleep 30 || echo $? >/tmp/foo
    end script

  Also, the post-SIGTERM loop ends prematurely because killall5 supports
  a maximum of 16 omitted processes (LP#634460). In my case, the ssh
  (LP#603363), portmap, statd, and (obviously) rc upstart jobs are still
  running. Each iteration of the post-SIGTERM loop duplicates these
  processes in OMITPIDS. On the fifth iteration, the list overflows and
  killall5 terminates with exitstatus 1. The loop terminates
  prematurely, since it interprets killall5 failure as an indicator that
  all SIGTERMed processes have terminated.

  The attached sendsigs fixes both problems. It won't kill processes
  that are children of upstart processes. In doing so, it avoids the use
  of killall5(1), allowing SIGTERMed processes the full ten seconds to
  shut down gracefully before SIGKILL. If killall5 had parent process
  checking, using that would be faster, but the fixed omitpid list size
  would still be a problem. Doing it "by hand" in the shell is
  reasonably fast, since there shouldn't be many processes still
  running.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/sysvinit/+bug/639940/+subscriptions